For example, in a production process of semiconductor devices, presence of foreign matter or pattern defects such as a short-circuit and a disconnection (defects described hereinafter include foreign matter and pattern defects) on a semiconductor substrate (wafer) causes failures including an insulation failure and a short-circuit in the wiring. Further, as the circuit pattern formed on a wafer becomes finer, a finer defect also causes an insulation failure in a capacitor and destruction of a gate oxide film or the like. As for defects, matter appearing from a movable unit of a transporting device, matter generating from a human body, matter produced by a reaction of process gas in a process device, and matter beforehand mixed in agents and materials are mixed due to various causes and in various states. Hence, detecting a defect taking place during the production process and determining the source of the defect in a short period of time to thereby prevent defective products are important to mass-product semiconductor devices.
Heretofore, as a method of ascertaining the cause of a defect, there has been a method in which the position of the defect is first identified by a defect inspection device and the defect is precisely observed and/or classified by use of a Scanning Electron Microscope (SEM) or the like and is compared with a database, to thereby estimate the cause of the defect.
Here, the defect inspection device is an optical defect inspection device which emits light onto a surface of a semiconductor substrate using a laser to conduct dark-field observation of scattered light from the defect to thereby identify the position of the defect, or an optical appearance-inspection device or an SEM inspection device in which light of a lamp or a laser or an electron beam is emitted to detect a bright-field optical image of a semiconductor substrate and the image is compared with reference information to thereby identify the position of the defect on the semiconductor substrate. Such observation methods have been disclosed in patent literature 1 or 2.
Additionally, as for the device to precisely observe a defect by an SEM, there have been respectively described in patent literature 3 to 5 a method and a device in which by use of positional information of a defect on a sample detected by a second inspection device, the position on the sample is detected by an optical microscope installed in the SEM defect inspection device to correct the positional information of the defect on the sample detected by the second inspection device and then the defect is precisely observed (reviewed) by the SEM defect inspection device as well as an operation in which when the defect is observed by the SEM defect inspection device, the height of the sample surface is optically detected to be aligned with a focal position of the SEM.